ICS 65.040.20  
 
Reference number  
DRS 230: 2019  
© RSB 2019  
  
 RWANDA 
STANDARD  DRS 
230  
 
Second edition  
2019 -mm-dd 
(Reaffirmed 2019 -mm-dd) 
Post Harvest Handling and Storage (PHHS) 
of milled rice  — Guidelines  
   
DRS 230: 2019  
©RSB 2019  - All rights reserved                  ii 
 In order to match with technological development and to keep continuous progress in industries, 
standards are subject to periodic review. Users shall ascertain that they are in possession of the latest 
edition  
 
 
 
 
 
 
 
 
© RSB 2019  
All rights reserved. Unless otherwise specified, no part of this publication may be reproduced or utilized 
in any form or by any means, electronic or mechanical, including photocopying and microfilm, without 
prior written permission from R SB. 
Requests for permission to reprodu ce this document should be addressed to : 
Rwanda Standards  Board  
P.O Box 7099 Kigali -Rwanda  
KK 15 Rd, 49  
Tel. +250 788303492  
Toll Free: 3250  
E-mail: info@rsb.gov.rw  
Website: www.rsb.gov.rw  
ePortal: www.portal.rsb.gov.rw   DRS 230: 2019  
iii                ©RSB 2019  - All rights reserved  
 Contents  Page 
Foreword  ................................ ................................ ................................ ................................ ............................  iv 
1 Scope  ................................ ................................ ................................ ................................ ......................  1 
2 Normative references  ................................ ................................ ................................ ............................  1 
3 Terms and definitions  ................................ ................................ ................................ ...........................  1 
4 Requirements  ................................ ................................ ................................ ................................ .........  3 
5 Specific guidelines  ................................ ................................ ................................ ................................  4 
5.1 Pre-harvesting  ................................ ................................ ................................ ................................ ...... 4 
5.2 Harvesting  ................................ ................................ ................................ ................................ .............  5 
5.3 Threshing  ................................ ................................ ................................ ................................ ...............  5 
5.4 Drying of  grain  ................................ ................................ ................................ ................................ ...... 6 
5.5 Cleaning a nd sorting  ................................ ................................ ................................ ...........................  6 
5.6 Packaging  ................................ ................................ ................................ ................................ ..............  6 
5.7 Transportation  ................................ ................................ ................................ ................................ ...... 7 
5.8 Storage  ................................ ................................ ................................ ................................ ...................  7 
6 Major storage pests and their control  measures  ................................ ................................ ...............  7 
Annex  A (normative)  Major storage pests and their c ontrol measures for milled rice  ..............................  8 
. DRS 230: 2019  
©RSB 2019  - All rights reserved                  iv 
 Foreword   
Rwanda Standard s are prepared  by Technical Committees and approved by R wanda Standards Board (RSB) 
Board  of Directors in  accordance with the procedures of RSB, in compliance with Annex 3 of the WTO/TBT 
agreement on the preparation, adoption and application of standards.  
The main task of technical committees is to prepare national standards.  Final Draft Rwanda S tandards 
adopted by Technical committ ees are ratified  by me mbers of RSB Board of Director s for publication and 
gazettment as Rwanda Standards.  
DRS 230 was prepared by Technical Committee RBS/TC 3, Cereals, pulses, legumes and cereal products.  
Committee memb ership  
The following organizations were represented on the Technical Committee on Cereals, pulses, legumes and 
cereal products (RBS/TC 3 )  in the preparation of this standard.  
Paragraph of p articipants  
: 
Rwanda  Standards Board  (RSB) – Secretariat  DRS 230: 2019  
v                ©RSB 2019  - All rights reserved  
 Introduction   
Post harvest losses for wheat can occur at many points after harvest during drying, threshing, shelling, 
winnowing, sorting, aggregation, transport and storage.  Reducing post -harvest losses can increase the 
volume and value of grains within t he market and available for consumption and sale.  
This standard has been developed to take into account:  
a) the needs of the market for the quality wheat  grains;  
b) the need  to facilitate  fair domestic,  regional  and international  trade  and prevent  technical barriers  to trade 
by establishing a common trading language for crop producers, buyers and  sellers;  
c) the needs of the producers in gaining knowledge of market standards, conformity assessment and post 
harvest  handling;  
d) the need to transport the product in a manner that ensures keeping of quality until it reaches the 
consumer;  
e) the quality  and safety  parameters  of the product  should  meet before  they are put on  the market;  and 
f) the need to promote good agricultural practices  that will enhance wider market access, involvement of 
small -scale  traders  and hence  making  farming  a viable  means  of generating  income  DRS 230: 2019  
1                ©RSB 2019  - All rights reserved  
 Post Harvest Handling and Storage (PHHS) of milled rice (oryza ssp.) — 
Guidelines  
1 Scope   
This Draft Rwanda Standard specifies the guidelines for Post Harvest Handling and Storage (PHHS) of milled rice (Oryza  
spp.). 
2 Normative references   
The following documents are referred to in the text in such a way that some or all of  their content constitutes 
requirements of this document.  For dated references, only the edition  cited applies. For undated references, 
the latest ed ition of the referenced document (including any amendments) applies.  
1) RS 218, Warehouse for bagged storage of cereals and pulses — Requirements  
2) RS 231, Guidelines for storage of grains and pulses with practical recommendations  
3) RS EAS 128, Milled rice – Specification  
3 Terms and definitions   
For the purposes of this standard, the follow ing terms and definitions apply.  
3.1 
milled rice  
whole or broken kernels of rice (Oryza spp) from which the hulls and at least the outer bran layers have been 
removed  
3.2 
harvesting  
operation of gathering the crop with matured earheads  
3.3 
threshing  
operation of separating the grains from the crop with matured earheads using manual or power operated 
thresher  
  
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 3.4 
winnowing  
operation of separating the clean and matured grains f rom the threshing wastes like chaffy, immature grains, 
soil particles and other foreign materials  
3.5 
drying of grains  
operation during which the threshed grains are dried to the safe storage moisture content of 13% so as to 
undergo the next operations of cleaning, packaging and storage  
3.6 
parboiling  
pre-milling operation of soaking the paddy in water, steaming and drying to impart hydrothermal treatment to 
paddy so as to retain all the nutrients  
3.7 
parboiled milled rice  
milled  rice in which the starch has been gelatinized by soaking, steaming, and drying  
3.8 
grain cleaning  
operation of separating the clean and matured grains from the milling wastes like hull, stones, immature 
grains, soil particles and other foreign materials  
3.9 
destoning  
rice is passed through a specific gravity table that separates the product by density. Stones are separated 
from the rice  
3.10 
husking  
husk is removed from the paddy by passing the paddy through two tightly pressing spinning rubber roles in 
which one roll is spinning faster than the other  
3.11 
bran  
by product from rice milling consisting of the outer (pericarp) layers of the kernel with part of the germ  DRS 230: 2019  
3                ©RSB 2019  - All rights reserved  
 3.12 
foreign matter  
all organic and inorganic material other than rice grains, broken kernel s, other grains and filth  
3.13 
moisture content  
amount of moisture in the grain expressed as percentage of the total weight of the sample on wet basis  
3.14 
storage management  
storage  management includes the prophylactic treatment using the spraying of chemicals and the curative 
treatments like fumigants and insecticides  
3.15 
transportation  
process of moving of paddy/rice from one location to other location during different unit operat ions of post 
harvest handling  
3.16 
post harvest losses  
measurable quantitative and qualitative loss of rice occurred during the various post harvest operations like 
harvesting, shelling, drying, cleaning, transporting and storage.  
4 Requirements  
Throughout t he whole process of PHHS the following should be considered:  
g) the products being handled shall comply with RS EAS 128; 
h) hygiene conditions shall be maintained throughout the whole process of  PHHS;  
i) materials and equipment used shall comply with the requiremen ts of relevant Rwanda standards;  
j) chemicals and their use shall comply with national standards  and regulations; and   
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 5 Specific guidelines  
5.1 Pre-harvesting  
Farmers should be well prepared for the harvesting of paddy by arranging labours, harvesting tools, drying  
and threshing yard, store room, protecting the grain in the field from birds etc. Some of the guidelines for pre - 
harvesting are:  
a) prior to the harvest, it is important that farmers are already prepared for their postharvest activities and 
they should ensu re that: 
1) the equipment needed for their harvest and post harvest activities is available and in good working 
condition;  
2) they have identified the place of important activities like drying and threshing yard;  
3) there will be sufficient storage space for the  crop;  
4) the grain stores and used sacks have been thoroughly cleaned and disinfected;  and 
5) the residues of the old harvest (last season’s crop) has been removed from all cracks and crevices 
and disposed in a hygienic  manner.  
b) farmers should ensure the timely h arvest of the paddy crop to avoid losses and the following should be 
considered:  
1) the time of harvesting can be identified by the change of colour of the plant from green to yellow 
showing the maturity of grains;  
2) do not wait for stalks and leaves to dry bec ause they remain green in some of the hybrid and 
composite  varieties;  
3) drain out the water from paddy field about a week or 10 days before the expected harvesting time, 
which helps in employing mechanical  harvesters;  
4) paddy cultivated for obtaining kernels ( grains) should be harvested when the kernels are 
physiologically matured with 22 % - 25 % of moisture content;  and 
5) farmers can open a paddy in the field itself and test the hardness, size, shape and maturity of the 
grain inside the paddy and decide the tim e of harvesting.  
c) avoid pest infestation prior to harvesting;  and 
d) when paddy is in the stage of ready to harvest, the problem of eating of the grains by the birds should be 
controlled to minimize post harvest losses, the following measures should be followed in different unit 
operations.  DRS 230: 2019  
5                ©RSB 2019  - All rights reserved  
 5.2 Harvesting  
Harvesting activity shall be done as follows:  
a) the paddy crop is to be cut at the stalk 5 cm - 7 cm above the ground  level;  
b) paddy should be harvested when the grains are hard and matured with optimum moistur e percentage of 
20 % - 25 % to avoid field loss of grains by  shattering;  
c) harvesting before maturity means a low milling recovery and also a higher proportion of immature seeds, 
high percentage of broken rice, poor grain quality and more chances of disease attack during storage of 
grain;  
d) delay in harvesting results in grain shattering and cracking of rice in the husk and expose the crop to 
insects, rodents, birds and pests attack, as well as lodging;  
e) avoid harvesting during wet weather  conditions;  
f) harvesting  should  be done  by adopting  proper  method  and avoid  missing  of the secondary  tiller panicles;  
g) the harvested crop should be tied into a bundle and carry it to threshing yard without much transportation 
loss; 
h) harvested  material  shall be protected  from the rain and excessive  dew by  covering;  
i) harvested  paddy  should  be kept separately  for each  variety,  to get true to type variety  (grains);  
j) harvesting too much dried paddy crop leads to more field and transportation  losses;  
k) the contact of the earheads with soil shall be avoided as it can be source of contamination or attack by 
insects;  and 
l) harvested rice crop should be transported immediately to the threshing  yard.  
5.3 Threshing  
Threshing shall be done as  follows:  
a) the machine used for threshing shall comply with Rwanda relevant  standards  
b) threshing may be done by manual methods like beating the earheads with wooden sticks on a clean floor 
or by power operated multi crop thresher for large  quantities;  
c) techniques that cause damage to the grains such as severe beating  with sticks shall be avoided to 
prevent the damage of  grains;   
©RSB 2019  - All rights reserved                  6 
 d) when power operated power operated threshers are used, the clearance between the concave and 
cylinder should be adjusted so that the percentage of broken grains shall be  avoided;  
e) power operated  thresher should have operator safety arrangements like the belt and pulley guard as per 
the relevant standard;  and 
f) threshing  machine  should  not be a source  of contamination  including  by rust, paint, grease  etc,. 
5.4 Drying of  grain  
The following shall be considered in drying of milled rice:  
a) the drying of the grains shall be done immediately after  threshing;  
b) the rice grains shall be dried to 13.5 % moisture content prior to packaging and  storing;  
c) the drying area (concrete floor, mat, etc) shall be clean and  not be a source of contamination to the 
grains;  and 
d) where  heated  air is used  to dry the grains,  temperature  and drying  time shall be synchronized  so that they 
do not result  in adverse  effect  on the nutritional  composition  and quality  of the grains  in its intended  use. 
5.5 Cleaning and  sorting  
Cleaning may be done manually or by using machine:  
a) when power operated cleaning machine is used, care should be taken by adjusting the fan speed to 
reduce the loss of grain in the chaffy  outlet;  
b) the grains shall be aspira ted to remove all the straws, chaff and leafy vegetative  matter;  
c) defective (mouldy, discoloured, shrivelled, rotten, broken, insect damaged, etc) grains shall be removed;  
d) sorting shall be done before grading and any treatment; and  
e) grading shall be in accordance with RS EAS  128. 
5.6 Packaging  
Milled rice shall be packaged according the following:  
a) rice shall be packaged in clean and food grade packaging materials;  
b) rice shall be packed in containers which will safeguard the hygienic, nutritional, and organole ptic qualities 
of the products;  DRS 230: 2019  
7                ©RSB 2019  - All rights reserved  
 c) each package shall contain rice grains of the same type and of the same grade designation;  
d) packaging container shall be free from pests and contaminants; and  
e) each container shall be securely closed.  
5.7 Transportation  
Transporta tion of soybeans shall consider the following:  
a) the grains may be transported in vehicle itself (bulk) or in transportable container then the vehicle and 
container shall be clean, dry and free from undesirable odours and infestation;  
b) rice grain should be ha ndled and transported in such a way so that they remain well protected from sun, 
rain or other sources of excessive heat, objectionable odour and from any type of cross infestation;  
c) if the vehicle is not fully enclosed, it should have a covering such as ta rpaulin to keep out of the rain or 
any form of water  
d) transported grains should be well ventilated with dry air to remove moisture resulting from respiration of 
the grains and to prevent moisture condensation; and  
e) transportation of rice grains with chemical s and products in liquid form shall be  avoided.  
5.8 Storage  
Storage facility and management should be in such ways that preserve the safety and quality of rice grains 
and shall comply with RS 231 and RS 218.  
6 Major storage pests and their control  measures  
Measu res should be taken to control insect infestation using either physical, chemical, mechanical or 
biological means or combinations of these methods. The prevalent storage pest and their control measures 
are given in Annex A  
 
 
 
 
 
  
©RSB 2019  - All rights reserved                  8 
 Annex  A 
(normative)  
 
Major storage  pests and their control measures for milled rice  
The damages of major stored grain pests of rice along with their control measures are given below:  
Name of pest and figure of pest  Damage  Control measures  
1. Rice weevil  
Sitophilus oryzae (Linn.)  Adults and Larvae both bore into  
grains and feed on the grains  Two types of treatments are 
followed to control the infestation  
 
A)Prophylactic treatment.  
Use following Insecticides to 
prevent infestation in godown and 
stock of paddy/rice.  
 
Malathion (50 % E.C.): Mix 1  litre 
in 100 Liter of water. Use 3  litre 
prepared solution per 100 square 
meter area.  
 
D.D.V.P. (76 5 E.C.): Mix 1 litre in 
150 litre of water. Use 3 litre 
prepared solution per 100 square 
metre area. Do not spray on stock. 
Spray on walls and floors  of the 
godown as and when required or 
once in a month.  
 
3 Deltamethrin (2.5 % WP) : Mix 1 
kg. In 25 litre of water. Use 3 litre 
prepared solution per 100 square 
metre area. Spray on gunny bags 
after 3 months interval.    
2. Lesser grain borer  
Rhizoperth dominica (fabr.)  
 
 Beetles and larvae both 
penetrate the grain and feed. 
Sometimes, larvae feed on the 
waste flour produced by the 
adults. Heavy infestation makes 
the grain warm and moist, which 
leads to mould formation. It eats 
maily paddy ker nels but may also 
damage milled  rice. 
3. Khapra beetle  
Trogoderma granarium  
 Larvae are a serious stored pest 
but the beetle itself does not 
damage. First the larvae feed 
germ portion and later other parts 
of the  grains  
4. Saw toothed grain beetle  
 
Oryzaephilus surinamensis (Linn.)  Both beetle and larvae feed 
broken grains and damaged 
grains of other insects. They are 
usually found as a secondary 
pest together with other grain 
pests.  
 
 
 
DRS 230: 2019  
9                ©RSB 2019  - All rights reserved  
    
5. Red rust / Confused flour beetle  
Tribolium castaneum ( Herbst.) Tribolium 
confusum (J.du V.)  
 
 Beetle and larvae both do not 
cause damage to whole grain but 
feed on broken and damaged 
grains produced by milling and 
handling or infested / damaged 
grains of other  insects  B) CURATIVE TREATMENT:  
 
Use following fu migation insecticide 
to control infested stock  
/ godown of paddy/rice in airtight 
condition.  
 
 
 
1. Alluminium Phosphide:  
 
For stack fumigation use 3 
tablets/tonne and put polythene cover 
on infected stock. For godown  
fumigation, use 120 to 140 tablets per 
100 cubic metre area and keep 
godown structure airtight and closed 
for 7 days.  6. Tropical ware house  
moth  
Ephestia cautella (walk)  
 The moth is usually found in 
warehouses. The larvae feed on 
damaged or processed grains 
leaving the whole grains 
undamaged. In heavy infestation, 
larvae cover all available surface 
with webbing.  
7. Rice moth  
Corcyra cephalonica (Staint)  
 
 
 
 Larvae feed broken and processed 
paddy/rice. Larvae produce dense 
webbings. Whole grain kernels are 
bound into lumps.  
 
©RSB 2019  - All rights reserved                  10 
 8. Rodents  
 Rodents eat whole grains, broken 
grains, flour etc. They spill more 
grains than they eat. Rodents also 
contaminate rice grains with hair, 
urine and feces,  
which     cause     diseases   like Rat cage :  
 
Different types of rat cages are 
available in the market. Rates caught 
in cage can be killed by  
 
 cholera, food poisoning, 
ringworm, rabies etc. They also 
damage the storage structures 
and other accessories of store  
like wire and cable etc.  dipping  in water.  
 
Poison baits :  
 Anti-coagulant pesticide like zinc 
phosphate is mixed with bread or 
any other food stuff used as bait. 
Baits are kept for a week.  
 
Rat burrow fumigation:  
 
Tablets of Aluminum  phosphate 
are put in each hole and burrow 
and holes are blocked by  mud 
mixture to make airtight.  
 
 
DRS 230: 2019  
11                ©RSB 2019  - All rights reserved  
 Bibliography  
 DRS 230: 2019  
 
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